I think it's some of King's best work. It's worth reading at least one to see if you're into the series. The first one is harder to get into than the rest.
I read The Wastelands first. It reminded me a little of The Stand, but with more detail around Roland (main dude) and less background on what's going on in the world. It was interesting enough that I decided to go back and see what I'd missed.
Tried to read The Gunslinger and got bored after a little while - there are a few other characters, but it's mostly two dudes in the desert. The Drawing of the Three was more in the vein of Wastelands, and from there I blazed through each book as soon as it came out.
You may not realize it, but you've seen glimpses of the DT universe through most of King's books.